Brake lining and method of making same



Patented July 17, 1923.

UNITED. STATES PATENT OFFICE.

IZADOR J. NOV'AK, OF BRIDGEPORT, CONNECTICUT, ASSIGNOB TO. EAYBESTOS COM- PANY, OF BBIDGEPORT, CONNECTICUT, A CORPORATION 01 CONNECTICUT.

BRAKE LININ G AND METHOD OF MAKING SAME.

No Drawing. Application filed May 10, 1928, Serial N0.-838,128. Renewed January 14, 1988.

This invention relates to improvements in brake linings, and refers more particularly to an improved woven brake lining havlng wear, frictional and manufacturing char-' and combinations thereof), the generalmethod of procedure consists in dissolving.

the desired binder in some suitable commercial solvent such as gasoline, kerosene, benzol and like liquids. The raw woven tape is saturated with the saturating solution comprising a binder and solvent materials, and after saturation, the solvent is dried out of the woven tape by the application of heat.

This method of incorporating a solid fusible asphalt to serve as a binding agent, would be satisfactory were it not for the fact that the asphalt or pitch does not perfectly dissolve in the above mentioned solvents much below the melting point of the asphalt. As these solvents mustbe used cold, due to their very low flash point, the solution is highly colloidal, and in attempting to saturate a filtering material such as asbestos tape, a large portion of the colloidal binder is left on the surface. When the solvent is removed, the binder is left on the surface in a layer, the thickness of which i tionable excess of sur ace deposited which causes the undesirable results 'above mentioned. I

Generally speaking, any saturation with a gilsonite solution which deposits more than twelve per cent total residual binder, may be considered unsafe from the standpoint of satisfactory brake action. When it is considered that from one-half'to one-third of the saturant is concentrated at the surface, it can readily be appreciated that the interior binder on which the continued wear of the brake lining under hard-service depends, may not regularly be higher than seven or eightper cent, and be accompanied by good action. This would indicate that severe service. would rapidly destroy ordinarily good gilsonite lin1ng, which has been found to be the case.

When this type of brake lining is subjected to high temperatures, as frequently occurs in conditions of'strenuous service, the surface binder burns 0r Wears away, leaving the slightly protected interior to disintegrate rapidly. Thus good gilsonit e treated lining has very satisfactory frictional characteristics but comparatively poor wear resistance, other factors being equal.

The present invention relates/to the de; velopment of a saturant and method of man ufacture of woven asbestos brake lining which carries the frictional advantages of the above type, and eliminates many of its disadvantages. such as the unsatisfactorily I tion.

It has been found that by the use of a combination of refined water gasp-tar and petroleum oil in the correct proportion,v which can be determined by trial, that brake linings can be produced-. first-that have excellent frictional qualities under all conditions, second-that contain a high percentage of binder without. undesirable surface filtration, and thirdpossessing the desirable characteristics of hardening in service without' imparting frictional qualities, and giving long satisfactory wear under severe conditions.

' tar consists essentially in the removal of the v p'resent process, but is an advantage due to attendant condensed water. by distillation. This refining is not essential to its use in the easier handling of the saturant in production. I

The term etroleum oil included as an ingredient in he saturant, is intended-to inelude all grades and varieties of mineral oils in any stage of the refining process. It has been foun oil will answerthe purpose. Asphaltic base oils generally give somewhat better results than paraflin base oils, but the general effect of. adding an oil to the watergas tar in the use of the combination as a saturant for brake lining, is practicallythe same.

Thus for'example, I have used California, Mid-Continent, Texas, heavy and light Mexican oils in various grades'from the crude I petroleum to solid asphaltwith excellent results. Paraflin base oils as well as straight parafiin also have been successfully em- 'l he 'method of making this improved brake lining consists in saturatin the woven asbestos tape in. a suitable com ination or mixture of the above described materials, and heatin vthe saturated tape until the more volati e portions have been driven off, leaving a binder which bears a predetermined ratio of saturant retained, to the saturant absorbed. This ratio varies with the different oils, but for any one combination, a satisfactory ratio ma be determined by trial. The ratio is varie by varying the de ee of heat treatment.

' he following is a detailed description of a typical method which gives more satisfactory results. The saturant consists of thirty parts by weight of 14 Baum mixed base refined Mexican crude petroleum, and

seventy parts of refined water gas tar,

thoroughly mixedv and heated to 150 F.

The woven asbestos covered wire tape is prepared by rolling between pressure rolls so that upon complete saturation in the above saturant followed by clean scraping of the I is saturated comp etel surface it shows a weight increase of 45% to 50% on theori 'nal wei ht. The tape an the surface scraped clean, after w ich the product is I cured at a tem erature'of substantially 450 F., for thirtyve minutes, or until the ratio of saturant retained to the saturant absorbed that many different varieties ofis between .45 and .50. The lining is then use.

The above brake lining shows in surface varied widely and still produce brake lin'-' ings of high efiicienc and longwear without departing from t e spirit of this invention.

For example, in the above described typical method the residual saturant may vary from 12% to 22% and the condition of cure from .35 to .55 without producing defective material. This is due to the flexibility of the saturant and binder mixture for brake linings.

By the term incombustible fibre used in the following claims is indicated any fibre orfibrous mixture which consists essentially of asbestos, or a like incombustible fibre.

I claim as my invention:

1. Frictional elements consisting of asbestos fibre having incorporated therewith a solid residue obtained from the heat treatment of a mixture of water gas tar and petroleum oil.

2.' As a new product of manufacture, fric tion elements comprising incombustible fibre.

having incorporated therewith the residue from the heat treatment of a mixture containing Water gas tar and petroleum. II

3. A :method of making frictional material consisting in saturating woven incombustible fibrous material with a saturant consisting essentially of water gas tar and petroleum oil, and heat treating the saturated material to improve its frictional qualities.

rolled to the desired size, and is ready for 4. A method of producing friction elements, comprising saturating an 'incombustible fibrous base with a saturant including water gas tar and petroleum,'and heat treating the saturated base to improve its, frictional qualities.

5. A meth d ments consisting in saturating woven asbestos, covered wire tape with a saturant of producing frictional ele consisting essentially of water gas tar and petroleum oil, heat treatingthe tape to remove the volatile portions and retaining in the tape a predetermined amount of saturant. I

6. A method of making frictional material consistmg in saturating incombustible fibrous material with a saturant consistingessentially of water gas tar and petroleum 8. As a new product of manufacture, friction elements comprising incombustible fibre haying incorporated therewith as a hinder, the residue obtained from the heat treatment of a mixture containing Water gas tar and a mineral hydrocarbon.

IZADOR J. NOVAK. 

